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Turtle Sense

Cell phones for Sea Turtles and beyond -- creating an extremely low powered remote data recorder and sensor for monitoring wildlife, etc...

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This very low powered, inexpensive remote data recording system was first designed to monitor the nests of endangered sea turtles, but can be adapted for many other purposes. Designed to withstand a harsh ocean beach environment, an ultra low powered sensor and microprocessor are combined on a tiny circuit board for applications in difficult locations. For turtle monitoring it is encased in a small plastic egg. This "Smart Sensor" - buried in the sand on top of a nest - measures, records and evaluates motion and temperature for several months. The Smart Sensor is attached by cable to a cell phone board which sends regular reports on the activity in the nest. The goal is to predict hatching dates from motion of the embryo in the egg or from motion of the egg as the hatchlings cut through the leathery egg or both. The smart sensor and cell phone board can be easily modified with other sensors or wireless communication.

The sea turtles found in the waters of Cape Hatteras National Seashore are protected by the U.S. Endangered Species Act, an extremely powerful law, that must be followed and administered by the National Park Service (NPS). While the NPS must protect the Seashore’s nesting sea turtles, the NPS also is obligated to uphold it’s mission and make the Seashore available to people for “enjoyment, education, and inspiration.” As the popularity of the Seashore has grown, it has become increasingly difficult for the NPS to meet its obligations to both people and sea turtles. The goal of Turtle Sense is to help people and sea turtles share the beaches of the Seashore in a way that benefits both humans and sea turtles.

Today, when a sea turtle nest is found on a Seashore beach, a small enclosure is built around the nest to keep pedestrians and vehicles away. About 50 to 55 days later the nest closure is expanded, often closing the beach to vehicular traffic. Because there is no reliable way to predict when tiny turtles will emerge from their nests near the duneline and parade to the surf, closures can sometimes last for more than a month. 

Turtle Sense system design

The Smart Sensor (the right half of the diagram above) uses an accelerometer to record changes in acceleration up to 400 times per second.  The readings are analyzed by the microprocessor to produce a profile summary of the forces acting on the sensor.  A new profile is created every 15 seconds to six minutes. Because it is not possible to transmit data from underneath wet salty sand, a set of summaries are uploaded to a separate Communications Unit (the left half of the diagram) at least once a day and as often as every hour.  The Comm Unit and the Smart Sensor are connect by Cat5e Shielded cable, which is typically about 20 feet (6 meters) long, but can be much, much longer if needed.  The Comm unit is controlled by another microprocessor which controls the communication with the Smart Sensor and also controls a plug-in cellular communications board.  Cellular communication uses the bulk of the power needed by the system, so its power supply is powered down when communication is not needed.  It is typically only powered up for a few minutes each day.  The entire device is powered by a battery pack of 8 rechargeable AA NiMH cells.  This is enough power to run the system for many, many months.

In order to keep track of multiple nesting sites, we also created a hand-held communications device that is used to test the sensors, check for good cell phone reception, and register the date and GPS location of the nesting sites.  Since this device is small and portable, it can be carried along with Smart Sensors on the daily beach patrols of park personnel.  When nests are found, they are excavated and the eggs are counted.  At that time, a Smart Sensor is placed on top of the nest, and it is connected to the hand-held device to register the nest.  Testing and registering the sensor just takes a few minutes.  Then the cable is buried, with its 9-pin Molex connector sealed in a plastic pill bottle.  The location of the end of the cable is marked with a stake.

After a few days or weeks, a larger comm unit is brought to the nest site and connected to the sensor.  This Comm unit is housed in sealed PVC pipe in a foundation of concrete. The comm unit enters a sleep mode if no sensor is plugged in. It powers up fully when a Smart Sensor is connected, and starts sending reports.

Detailed reports are regularly uploaded to a server on the Internet.  These text file reports are readable by humans and machines.  Eventually, there will be a web based interface for controlling the parameters of the system and viewing data.  If we are successful, an automated system will accurately predict hatching events and send alerts of pending hatching to wildlife managers, researchers and the general public.  To...

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  • 2 × ***COMPLETE BOMs FOR CIRCUIT BOARDS ARE IN THE LIST OF LINKS*** The links are labeled "Custom Smart Sensor BOM" and "Custom Communicator BOM".
  • 1 × Smart sensor custom circuit board (1" X1") Components include TI MSP430FR5739 processor, ADXL 362 motion sensor and ADM 3491 transceiver. See "Custom Smart Sensor BOM" link in left column.
  • 1 × Communications custom circuit board (3.2" X 1.5") components include TI MSP430FR5739 processor, headers for cell phone board, power supplies, analog switches, and ADM 3491 transceiver. See "Custom Communicator BOM" link in left column.
  • 1 × Janus plug-in M2M cell phone boards 5 interchangeable boards that are certified to work with different telecoms around the world -- NOTE! This 3rd party board is not open hardware, but it is FCC approval and carrier certified, which is a difficult, and expensive process. We are not aware of any open hardware, FCC approved and carrier certified cell phone boards.
  • 1 × Cell phone antenna Penta band with right angle SMA connector
  • 1 × Sheilded underground cat 5 cable Connects buried sensor to communications unit -- RF transmission through wet salty sand is not possible. Cable can be several hundred feet long if needed.
  • 2 × 9 pin Molex connectors with gold contacts Male and Female Connects the cable from the egg to the communications units. The communications units can be connected several weeks after the sensor egg is placed in a nest
  • 1 × Epoxy coating for smart sensor board after fabrication Coated to make it water proof - see assembly instructions. Tap Plastics "Easy Cast" two part epoxy resin
  • 1 × Flexible silicon turtle egg mould Made from casting a ping-pong ball - see assembly instructions. Tap Plastics "Platinum" silicone two part mold making material
  • 1 × Polyurethane quick cast liquid (about 40cc) For creating the cast "egg" sensors and securing the molex connectors to the cables - see assembly instructions. Tap Plastics "Quik-Cast" two part polyurethane casting resin

View all 48 components

  • 2015 Update

    Samuel Wantman08/28/2015 at 03:51 0 comments

    We've been hard at work on the next phase of this project. We've installed a capacitive moisture detector in the egg sensor, changed from 8 AA NiMH batteries to 3 AAAs, added a solar cell that keeps the batteries charged up until they totally die (about 10 years?), and changed the connection between the sensors and the communications tower to a single RG6 coax cable. The coax will power the sensors and also carry data. A single communications tower will be able to handle multiple sensors simultaneously (we're not sure how many yet, but it should be about a couple dozen). The coax should be much more reliable than the Cat5 cable we have been using, and make it easier and cheaper to build and maintain. A coax cable can be repaired in the field in about a minute. There will be lots of ways to extend the system using SPI, I2C, and analogue and digital connections. Software will be field updatable, and we've been working on server-side visualization of the data. For more information about our progress, please visit

    The National Park Service has been using the system this summer with excellent results. One sensor failed, but every other nest has provided data that was used to accurately predict when baby sea turtles would emerge from their nests. Most of our predictions were about 4-5 days before emergence, and the prediction was usually correct within a day. We were able to spot nests that were infertile, and were only incorrect when we predicted an infertile nest, but in fact less than 10 percent of the eggs hatched. While we missed that handful of hatchlings, the NPS was able to rescue about 75 hatchlings from almost certain drowning because of our system. We knew that they had hatched, but they hadn't yet emerged. A storm and high tide threatened to drown the hatchlings who were trapped in the nest with a hard crust above it. Because the NPS knew from our system that there were hatchlings, they were able to rescue them just in time.

  • Unintended Consequences (mostly positive)

    Samuel Wantman10/02/2014 at 14:23 0 comments

    I just returned from nine days visiting our two test sites in North Carolina. While there, I got a chance to see baby sea turtles making their way to the ocean and to talk with wildlife managers and biologists. I learned quite a bit from the trip. We went out for several nights to visit a nest where I had predicted a boil using the data from our sensor. The turtles emerged two days later than expected, but that was not surprising considering that the temperature had been cooling down in the prior two weeks, and the previous nests had hatched during warmer periods. The boils often occur between sundown and about 10:00 PM, which is when we usually gave up and went home. This nest ended up boiling a little after midnight.

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  • User Interface

    Samuel Wantman09/16/2014 at 03:15 0 comments

    We want to make Turtle Sense as simple to use as possible. So, at the most basic level, setting it up, you just plug the connector coming from the turtle egg Smart Sensor into the connector attached to the communications tower. The device, which has been asleep, wakes up and starts collecting data and sending out reports. When you unplug the devices, they go back to sleep until the next time.

    But that is just the surface of how we plan to have users interact with the device. We made these units for use by the National Park Service, but the NPS is just the representative for a much bigger group of users: wildlife managers, researchers, eco-tourists, fisherman, and the general public.

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PointyOintment wrote 03/19/2015 at 03:14 point

You might be interested in #Project Apollo

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Samuel Wantman wrote 08/05/2014 at 22:42 point
We are measuring the temperature in the nest. In our situation, we only have official permission to install a single sensor in the nest. Our hope is to use the temperature data with the motion readings to refine our estimations on the total incubation period. It seems that the effect of global warming on the sex of sea turtles is a hot button topic. As soon as our design stabilizes, we will be making units available at cost for researchers around the world. We will also be looking for people to help test our units on GSM networks outside of the US, as we hope to make the device compatible with cell phone networks all over the world. We will also be encouraging researchers to expand on our software so that it is applicable for other uses with sea turtles and with many other egg-laying species.

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jlbrian7 wrote 08/09/2014 at 10:45 point
I don't think her work dealt with global warming. Apparently it is not known with certainty what temperature ranges produce males and what produce females. I think it is hard to know what impact climate change has when you don't have a reliable baseline.

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jlbrian7 wrote 08/05/2014 at 22:32 point
My wife was awarded a Fulbright to study the arribada in Costa Rica. She wanted me to see if I could build a data logger that would capture the temp at different depths of the nest, and once they hatched they would sex the turtles. Ultimately I could not do it cost effectively, but I could nearly compete with the consumer products because they can be pricey for what they wanted to accomplish. If you are interested I can see if she can suggest some white papers.

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